Barack and Michelle Obama Tuesday launched a youth leadership summit with an accent on social service, with Britain's Prince Harry on hand.

The two-day event was billed as an opportunity for notable young activists and leaders from around the world to learn from each other, and from experts.

Given the Obamas' starpower, well-known names were scheduled to appear, including the British royal, rapper Common, singer Gloria Estefan, composer Lin-Manuel Miranda, and former Italian prime minister Matteo Renzi.

Some 500 people from 60 countries, who have made some form of social impact in their communities, were invited to attend the summit in the Midwestern city where Obama first entered politics and where his presidential library will be built.

They were either nominated to attend or were chosen from among 20,000 applicants.

The former US president, who has made cultivating the next generation of young leaders and community activists a centerpiece of his post-White House work, told the assembled group that he hoped to learn from the summits' panels and discussion groups.

"In many ways, we want to learn from you as much as we want to maybe share some of what we've learned," Obama said.

"This is a big brainstorming session. This is a big hackathon. This is an experiment in us trying to have a collective conversation."

Politics was left out for the most part, with only brief mentions by some of Tuesday's speakers.

In opening remarks, Marietje Schaake, a member of European Parliament, alluded to some of the controversial politics roiling American discourse -- including President Donald Trump's yet-unfulfilled promise to build a wall along the US-Mexico border.

"Closing borders or erecting walls are not the answers to today's global challenges," Schaake said, adding that societies should not turn inward.

"It is a matter of leadership and civic duty to shape the society of the future based on the democratic values," she said.

Britain's Prince Harry offered an introspective account of his call to service - saying spending 10 years in the military was a major influence, as was his late mother Princess Diana.

"I will always look up to her as being my ideal role model, because everything that she did and the way she did it, was having an impact, it was making a difference," he said.

Prince Harry supports a number of charitable activities and projects, including those aimed at helping children.